if (typeof window !== 'undefined') {
    var waitSeconds = 100;

    var head = document.getElementsByTagName('head')[0];

    var isWebkit = !!window.navigator.userAgent.match(/AppleWebKit\/([^ ;]*)/);
    var webkitLoadCheck = function (link, callback) {
        setTimeout(function () {
            for (var i = 0; i < document.styleSheets.length; i++) {
                var sheet = document.styleSheets[i];
                if (sheet.href == link.href) {
                    return callback();
                }
            }
            webkitLoadCheck(link, callback);
        }, 10);
    };

    var cssIsReloadable = function cssIsReloadable(links) {
        // Css loaded on the page initially should be skipped by the first
        // systemjs load, and marked for reload
        var reloadable = true;
        forEach(links, function (link) {
            if (!link.hasAttribute('data-systemjs-css')) {
                reloadable = false;
                link.setAttribute('data-systemjs-css', '');
            }
        });
        return reloadable;
    };

    var findExistingCSS = function findExistingCSS(url) {
        // Search for existing link to reload
        var links = head.getElementsByTagName('link');
        return filter(links, function (link) {
            return link.href === url;
        });
    };

    var noop = function () {};

    var loadCSS = function (url, existingLinks) {
        const stylesUrl = url.includes('styles.css') || url.includes('style.css');
        return new Promise((outerResolve, outerReject) => {
            setTimeout(
                () => {
                    new Promise(function (resolve, reject) {
                        var timeout = setTimeout(function () {
                            reject('Unable to load CSS');
                        }, waitSeconds * 1000);
                        var _callback = function (error) {
                            clearTimeout(timeout);
                            link.onload = link.onerror = noop;
                            setTimeout(function () {
                                if (error) {
                                    reject(error);
                                    outerReject(error);
                                } else {
                                    resolve('');
                                    outerResolve('');
                                }
                            }, 7);
                        };
                        var link = document.createElement('link');
                        link.type = 'text/css';
                        link.rel = 'stylesheet';
                        link.href = url;
                        link.setAttribute('data-systemjs-css', '');
                        if (!isWebkit) {
                            link.onload = function () {
                                _callback();
                            };
                        } else {
                            webkitLoadCheck(link, _callback);
                        }
                        link.onerror = function (event) {
                            _callback(event.error || new Error('Error loading CSS file.'));
                        };
                        if (existingLinks.length) {
                            head.insertBefore(link, existingLinks[0]);
                        } else {
                            head.appendChild(link);
                        }
                    })
                        // Remove the old link regardless of loading outcome
                        .then(
                            function (result) {
                                forEach(existingLinks, function (link) {
                                    link.parentElement.removeChild(link);
                                });
                                return result;
                            },
                            function (err) {
                                forEach(existingLinks, function (link) {
                                    link.parentElement.removeChild(link);
                                });
                                throw err;
                            }
                        );
                },
                stylesUrl ? 5 : 0
            );
        });
    };

    exports.fetch = function (load) {
        // dont reload styles loaded in the head
        var links = findExistingCSS(load.address);
        if (!cssIsReloadable(links)) {
            return '';
        }
        return loadCSS(load.address, links);
    };
} else {
    var builderPromise;
    function getBuilder(loader) {
        if (builderPromise) {
            return builderPromise;
        }

        return (builderPromise = System['import']('./css-plugin-base.js', module.id).then(function (CSSPluginBase) {
            return new CSSPluginBase(function compile(source, address) {
                return {
                    css: source,
                    map: null,
                    moduleSource: null,
                    moduleFormat: null,
                };
            });
        }));
    }

    exports.cssPlugin = true;
    exports.fetch = function (load, fetch) {
        if (!this.builder) {
            return '';
        }
        return fetch(load);
    };
    exports.translate = function (load, opts) {
        if (!this.builder) {
            return '';
        }
        var loader = this;
        return getBuilder(loader).then(function (builder) {
            return builder.translate.call(loader, load, opts);
        });
    };
    exports.instantiate = function (load, opts) {
        if (!this.builder) {
            return;
        }
        var loader = this;
        return getBuilder(loader).then(function (builder) {
            return builder.instantiate.call(loader, load, opts);
        });
    };
    exports.bundle = function (loads, compileOpts, outputOpts) {
        var loader = this;
        return getBuilder(loader).then(function (builder) {
            return builder.bundle.call(loader, loads, compileOpts, outputOpts);
        });
    };
    exports.listAssets = function (loads, opts) {
        var loader = this;
        return getBuilder(loader).then(function (builder) {
            return builder.listAssets.call(loader, loads, opts);
        });
    };
}

// Because IE8?
function filter(arrayLike, func) {
    var arr = [];
    forEach(arrayLike, function (item) {
        if (func(item)) {
            arr.push(item);
        }
    });
    return arr;
}

// Because IE8?
function forEach(arrayLike, func) {
    for (var i = 0; i < arrayLike.length; i++) {
        func(arrayLike[i]);
    }
}
